Article of manufacture and process of making same



Feb; 23 1926. 1,574,380

H. A; ENDRES ARTICLE OF MANUFACTURE AND PROCESS OF MAKING SAME FiledJune 192s l essune 141w I E PRODUCT ,Hmamr A. ENDRES. INVENTOR.

ATTORNEY.

Patented Feb. '23, 1926.

UNITED STATES PATENT OFFICE.

HERBERT A. ENDRES, OF LOMPOC, CALIFORNIA, ASSIGNOR TO THE CELITECOMPANY, 01 LOS ANGELES, CALIFORNIA, A CORPORATION OF DELAWARE.

ARTICLE OF MANUFACTURE AND PROCESS OF MAKING SAME.

Application filed June 23, 1925. Serial No. 89,142.

To all whom it may concern:

Be it known that I, Hmmnnr A. ENDRES, a citizen of the United States,residing at Lompoc, county of Santa Barbara, State of California, haveinvented a new and useful Article of Manufacture and Process of MakingSame, of which the following is a specification.

This invention relates to the process of manufacturing a finely dividedmaterial having a large surface area, by chemical disintegration ratherthan by grinding or milling. The product made in accordance with thisinvention is particularly adapted for use in filtration,de-emulsification, thermal insulation, an ingredient in concrete andcements, a carrier for catalytic agents andas a filler in numerouscompounds such as rubber, phenol-condensation products, polishes, etc.,wherever a fine porous product is needed.

It has been known for some time that lime and silica slowly react, andalthough steam under pressure accelerates the action slightly, thereaction takes a number'of hours and even then is very incomplete. Thiscombination of lime and silica has been used in the manufacture ofsand-lime brick. I have found, however, that when a water suspension ofa finely ground or powdered silica is treated with lime, at temperaturesnear the boiling point, .a rapid reaction takes place, whereby avoluminous, almost gelatinous mass of hydrated mono- -calcium silicateis produced By calcining the wet mass at a high temperature a veryfinely divided material is obtained.

Mechanical means of grinding or reducing the particles of solidmaterials are limited in their application to a product which will ass250325 mesh screens, but by means 0 my invention I can make a materialwhich will have an average particle size of about one micron (0.0000394inch) or less, corresponding to a material of about 6000 mesh.

The finely divided silica used by me in the manufacture of a finelydivided product may be pulverized sand or quartz, but preferablydiatomaceous earth, otherwise known as infusorial earth, tripoli,diatomite, kieselguhr, or fossil flour. Some attempts have been made topulverize crude diatomaceous earth to a fine state of division, but ashas been said, mechanical means of disintegration have certainlimitations as to minimum particle size obtainable. In my process Iutilize certain chemical forces which make it possible to obtain a verymuch finer particle size.

My invention is disclosed on the accompanying diagrammatic flow. chart.VVhenever it is desirable to calcine limestone to make lime for myprocess, limestone is charged into the kiln or other suitable furnace(1) and the carbon dioxide gases utilized later on. The burned lime maybe ground or otherwise reduced to the required state of division in anysuitable apparatus (6) and then conveyed to a mixing tank or reactionchamber (2) which may be, for example, an open top tank, having means(9) of supplying cold or'previously heated Water thereto, means (7) ofsupplying heat, for example, by means of steam coils, and means (8) ofsupplying powdered silicious material thereto. The tank (2) should beprovided with suitable agitating means.

At the completion of the reaction the resulting product may be conveyedas indicated by (11) to suitable dewatering or separating apparatuswhich may consist of vacuum type filters or settling tanks. Thedewatered product is then conveyed by means (12) to a calciner ofsuitable design (4) The eflluent from the separating apparatus (3) maybe returned by means (14) to the reaction chamber or allowed to go towaste. As an alternative method of procedure the product of the reactionchamber (2) may be conveyed as indicated by means (13) directly to thecalciner (4).

As an additional variation in my process, tank (2) may be merely used asa mixing chamber and the mixed mass conveyed by means (21) to anautoclave or pressure tank (22) having suitable means of supplying steam(23) or heat thereto, wherein the reaction may take place atsuper-atmospheric pressure and temperatures in excess of 212 F. Theproduct of such reaction is then conveyed by suitable means (24) to thecalciner or roaster (4). Or the mixing operation in tank (2) may beeliminated and the lime, water and silicious material fed directly intothe autoclave or pressure tank (22). This tank should be provided withappropriate agitating or mixing means so as to assure thorough mixing ofthe in.- g'redients and prevent undue caking or ag lomeration.

Zfter calcination has taken place, the resulting finely divided materialmay be conveyed as indicated by (18) to a carbonatlon chamber (5)wherein it may be exposed to a large volume of air or other CO bearinggases. The carbon dioxide resulting from the calcining operation at (1)may be conveyed by means (15) and (17) to this,

chamber. After carbonation the product is in finely divided conditionand ready for commercial uses. As an alternative step in my process, thecarbon dioxide gases result ing from the calcining operation at 1) maybe conveyed by means (15) and (16) to the calciner (4) and the calciningand carbonating operations performed simultaneously.

Upon adding lime to the water suspension of diatomaceous earth thereaction takes place quickly, but becomes very violent at temperaturesaround 212 F., and after boiling for a period of 1 hours, nodiatomaoeous structure is visible in the mass. The silicate which isformed is highly hydrated, becomes very bulky and water must .be addedfrom time to time as the reaction proceeds, to compensate for loss byevaporation and prevent a stiff mass from forming. The exact compositionof the product of this reaction is not definitely known, although itappears that a calcium silicate having the composition CaO.Si() .2 H Ois formed in large amounts.

When this highly hydrated calcium silicate is dehydrated by calcinationat temperatures ranging from 1000 to 1600 F. a pulverulent, impalpablematerial is obtained,

- having a particle size varying somewhat with the amount of lime usedduring the reaction, the amount of water added, and the temperature ofcalcination. Samples have been prepared in which the average particlesize was essentiall below one micron but much coarser gra es can beprepared by longer heating of the mass, reducing the quantity of limeused, etc. When an excess of lime is used, particle size becomessmaller, probably due to a more complete and rapid combination of thecomminuted silica and the lime and consequently a more completedissociation during calcination. The product resulting from suchcalcination consists essentially of calcium metasilicate.

Whenever more lime than is theoretically needed to form the silicate hadbeen added, the product contains some finely divided anhydrous lime(CaO). If the calcination is carried out below 1500" F. in the presenceof carbon dioxide (CO theexcess lime present forms minute particles ofcalcium carbonate so that the final product is a mixture of calciummetasilicate and calcium caroughly dehydrates the mass, stops crystalgrowth by rapidly removing the water which is the medium or vehiclethrough which the growth takes place and prevents the agglomeration andcoalescence which usually occurs when finely divided precipitatedmaterials are slowly dried. The action obtained during calcination isprobably similar to what would occur if a sealed light glass bulb partlyfilled with water was suddenly exposed to a high temperature. Watervaporizes rapidly and disrupts the particles, breaking them up intovarious fine segments.

One specific method of procedure in the operation of my process is asfollows: 00 pounds of finely divided diatomaceous earth or other finelyground silicious material are dispersed in 500 pounds of water and themixture heated to boiling. About 56 pounds of freshly burned quick limeare then gradually added with constant agitation and more water is addedfrom, time to time as the reaction takes place, until a total of 500pounds of additional water are added. The mixture is then boiled forthree hours with constant agitation to prevent baking on the bottom ofthe container and the voluminous, highly hydrated mass is then partiallydehydrated or freed from excess entrained moisture on a suction filter.The still wet mass is then fed to a furnace operating at from 1000 to1600 F. where all water of hy- The dration is driven off and massreduced to a very fine state of division. Calcination at 1400 for abouthalf an hour gives very good results.

It is preferable to use excess quantities of lime as this increases thespeed of reaction in the heating and boiling chamber and by are used, isas follows: Crude limestone is' burned at a temperature about 1500 F.and

the quicklime added to a boiling suspensionof diatomaceous earth inwater in the approximate proportionsof112 pounds lime to 60 pounds ofdiatomaeeous earth. After kee ing the mixture at about 212 F. for a sucient length of time to assure the combination of all silica with thelime the mass is partly freed from mechanically held water in a suitabletype of filter or de-waterer, as for example, a continuous suctionfilter or settling tank, and is then charged to a suitable furnace oroven where it is subjected to a temperature of from 1000 to 1500 F. Thecarbonation of the CaO pro duced in calcining the hydrated mass may beaccomplished either in the furnace by performing such calcination in anatmosphere of CO or after calcination the product may be subjected tothe action of CO or the carbonation may comprise both methods. The COmay be easily obtained as a by roduct from the limestone-calciningoperation and used in the carbonation of the final calcined product.

The reaction produced by mixing lime with a boiling suspension ofdiatomaceous earth in water is so violent that I have found it advisableto dilute the suspension with large amounts of water in order to preventspattering and loss. As has been said before, the crystal growth isretarded and a finer product is obtainable from concentrated suspensionsand for this reason I have found that the following alternative methodof procedure may be adopted very successfully.

An autoclave or closed steam heated tank is filled with a suspension of120 lbs. of finely divided diatomaceous earth in 750 lbs. of waterand224 lbs. of lime dispersed in an additional 750 lbs. of water is mixedtherewith, the entire mixture is then kept heated for about 45 minutesat 15 lbs. pressure, 250 F., and at the end of this time,

or when reaction is completed, the mass is removed from the autoclaveand calcined and carbonated as described above By means of the abovealternative method of operation no water is lost by evaporation, thereaction takes place much more rapidly, it is not necessary to removeexcess water by filtration before the calcining operation, and as thereaction takes place rapidly. it is possible to make a very fineproduct. The

ingredients may be fed directly to the auto-' clave, or preferably, to amixer and then to the autoclave, so that one mixer can supply materialfor a number of the latter units.

By employing a suitable excess of lime (about three equivalents on theamount of diatomaceous earth or silica depending upon the activity ofthe lime)and a sufiiciently finely divided diatomaceous earth or silica,the heat of hydration of the lime can be utilized in carrying out thereaction, no further application of heat being necessary after the limehas been added to the hot suspension of diatomaccous earth or silica.

The product of this reaction is then calcined or it may be calcined andthen carbonated as described.

The product produced in accordance with my invention may be used as afiller in paints, dental powders and pastes, soaps, polishes and variousother compositions. The fine state of division of my final product givesa material having great surface area and for this reason it may be veryeffectively used as a carrier for catalytic agents as for nickle, forexample in the hydrogenation process. It may also be very effectivelyutilized as an absorbent for gases, moisture or other liquids andmalodorous substances. The product may be used. to great advantage inthe manufacture of rubber goods, such as tires, treads, containers, etc.and as a lubricant and water tightening agent for concretes or hydrauliccement compositions.

lVhat I claim is:

1. The process of producing a finely divided material comprising heatinga mixture of a finely divided silica and lime in water, and thencalcining the resulting product.

2. The process of producing a finely divided material comprising heatinga mixa l ture oi diatomaceous earth and lime in water, and thencalcining the resulting product. i

3. The process of producing a' finely I divided material comprisingmixing lime with a water suspension of finely divided silica, heatingsuch mixture to the boiling point until reaction occurs, and thencalcining the product of such reaction.

4. The process of producing a finely divided material, comprising mixinglime with a water suspension of disintegrated diatomaoeo-us earth,heatingysuch mixture to the boiling point until reaction occurs and thencalcining-the product of such reaction.

The process of making a finely divided material comprising mixing limewith diatomaceous earth, adding water to the mixture, aplying heatthereto until reaction occurs, removing the excess water from theproduct of such reaction and then calcining finely divided the partlydried'product.

6. The process of making a material, comprising mixing lime withdiatomaceous earth, adding water to the mixture, applying heat theretountil reaction occurs, removing the excess water from the product ofsuch reaction, calcining the partly dried product, and exposing thecalcined product to the action of carbon dioxide.

7. The process of producing a finely divided material comprising mixinglime with finely divided silica in the presence of water, maintainngsuch mxture at about the temperature of boiling water until reactionoccurs and then calcining the product of such reaction at a temperatureof from 1000 to 1600 F.

8. The process of making a new article of manufacture comprising mixinglime with disintegrated diatomaceous earth in the presence of Water,maintaining such mixture at about the boiling point until reactionoccurs, calcining the product of such reaction at a temperature of from1000 to 1600 F. and carbonating the product of such calcination.

9. The process of making a new article of manufacture comprising mixinglime with disintegrated diatomaceous earth in the presence of water,maintaining such mixture at about the boiling point until reactionoccurs, removing the excess water from the product of such reaction andthen calcining .the partly dried product at a temperature of from 1000to 1600 F. and carbonating the product of such calcination.

10. The process of making a finely divided material, comprisingmixinglime with diatomaceous earth, adding water to the mixture, applying heatthereto until reaction occurs, removing the excess Water from theproduct of such reaction, and subjecting the product to the action ofcarbon dioxide.

11. A new article of manufacture produced by mixing disintegrateddiatomaceuus earth with suflicient lime to combine therewith, producinga reaction by heating the- :mixture in the presence of water andsubjecting the product to the action of carbon dioxide.-

12. A new article of manufacture produced by mixing approximately 60.parts of disintegrated diatomaceous earth with 112 parts of lime byweight, causing a reaction by the addition of water and the applicationof heat and carbonating the product of such reaction.

13. As a new article of manufacture, a finely, divided materialresulting from the calcination of the product of reaction of lime andfinely divided silica in the presence of water.

14. Asa new article of manufacture, a finely divided material as setforth in claim 13, carbonated during ealcination.

15. A finely divided product obtained by calcination of the product of areaction of lime and diatomaceous earth in the presence of water.

As an article of manufacture a finely divided product 'asset forth inclaim 15, carbonated during calcination.

17. A new article of manufacture produced by mixing approximately 60parts of disintegrated diatomaceous earth with 112 parts of lime byweight, causing a reaction by the addition of water and the applicationof heat and calcination'of the product of such reaction. I

18. A new article of manufacture as set forth in claim 17, carbonatedduring the calcining operation.

19. The process of making a new article of manufacture comprisingmaintaining a hot mixture of finely divided silica, lime and Water untilreaction occurs, then removing the excess water from the product of suchreaction and finally calcining the partly dried product.

In testimony whereof I have hereunto sub-

